Dynamic elbow support

ABSTRACT

A dynamic joint support having proximal and distal support sections and means (46,60,66) for rigidly connecting each support section to bone and a pair of hinges (14) connecting each support section to each other and pivoting at the joint to cause movement of the support section and its corresponding attached bone through the movements of flexion and extension. The hinge (14) may be driven in its movement by a gear mechanism (30,70,74) which may be disengaged by means of a clutch (78). The dynamic joint support may also include a distraction mechanism for movement of the bones out of contact in the joint, while allowing for an active range of motion at the joint. &lt;IMAGE&gt;

FIELD OF THE INVENTION

The present invention relates generally to the treatment of injuries andcontractures of a major skeletal joint such as the elbow and, moreparticularly, to a dynamic elbow support for allowing the elbow to beflexed and extended either by the patient actively or passively or by acontinuous passive motion machine and maintain its alignment formanaging contractures.

BACKGROUND OF THE INVENTION

Flexion contractures or a tendency for muscles, tendons or scar tissueto shorten in skeletal joints are common after trauma and represent amajor challenge in the care of such injuries. For example, a contractureof 30°-40° in the elbow can severely reduce upper extremity function.

Current approaches to the treatment of elbow trauma have moreaggressively sought to prevent contracture and stiffness throughmovement. Methods of rigid internal fixation with sufficient stabilityto allow motion within days after injury rather than closed treatmentand immobilization in a cast have been developed. In the treatment ofdislocations, protected early motion is now begun as soon as the patientis comfortably able to do so.

However, the currently available techniques for the prevention ofcontracture are not uniformly successful. Early active motion alone canreduce the severity of contracture, but requires the patient's ownstrength, compliance and constant effort and the proper alignment andtracking of elbow cannot be insured. Passive stretching by a therapistcan be done on a very limited basis and is applied slowly, but suchtherapy risks the formation of heterotopic bone and myositisossifications. Dynamic splints may be used, but these require pressureon the sometimes sensitive or injured soft tissues of the arm andforearm, and may not be possible, i.e. burn injury, or may reducepatient compliance. Examples of such splinting devices include aturnbuckle orthosis or cast, reverse dynamic sling, polycentric castbrace hinges, or a hinged orthoses with rubber band traction.

Continuous passive motion (CPM) devices have been developed whichprovide early motion gains, but these devices do not normally allow thejoint to come to the extremes of motion which are the areas of greatestneed. Further, these devices are not designed to insure accuratetracking or stability of the elbow joint, but instead move the wristrelative to the shoulder or the humerus. These devices also rely ondirect pressure on the soft tissues and skin, and thus are subject tothe same limitations as the external splints discussed above.

Flexion-extension hinge distractors are hinged external fixators whichare designed to hold the joints such as the elbow in distraction whilepermitting an active range of motion. These include the Volkov elbowhinge-distractor and the Deland and Walker hinge distractor. Thesedevices require the placement of a pin or wire into or in closeproximity to the kinematic axis of the elbow, with the pin acting as themechanical axis of the device. Because these devices are difficult toalign over the axis of rotation, pin tracking problems can occur.Furthermore, the mechanical axis cannot be realigned without reinsertionof the pin. In addition, these systems do not permit passive driving ofthe joint through a range of motion.

An additional problem associated with the flexion-fixation hingedistractors is the placement of pins in close proximity to the joint.Because of the movement of skin over and relative to underlying bone,movement of the skin in this area with normal flexion and extension ofthe elbow in relation to a stationary pin can cause skin irritation andlead to infection. Such placement of the pins may also interfere withthe treatment of a fracture by internal fixation.

Because of limitations with the currently available methods to preventor treat joint injuries, patients often require surgical soft tissuerelease to improve the range of motion. Surgical release of contracturemust be followed by many months of intensive therapy and splinting tomaintain the gains in motion. Such maintenance is not uniformlysuccessful, as the splinting and traditional therapies applied sufferfrom the same limitations as discussed above. Moreover, oftentimes thecost of surgery and therapy, as well as the costs in time, lost wagesand rehabilitation can be significant.

SUMMARY OF THE INVENTION

In order to solve the problems described above, a dynamic joint supportis provided which includes proximal and distal external bracingsections, respectively connected to the upper arm and forearm onopposite sides of a joint. The bracing sections are rigidly connected totheir respective limbs through support rings which encircle at leastpart of the limb and are connected to internal bone through wires orpins.

A hinge connects the bracing sections to each other in the vicinity ofthe joint so that the hinge can pivot at the joint when the limbs aremoved through flexion or extension. The hinge includes an X-raytransparent material at the pivot point with target cross hairs so theaxis of the hinge can be aligned with the axis of the joint.

Appropriate adjusters are included with the external bracing sectionsfor adjusting the length and orientation of the bracing sectionsrelative to their respective limbs and to the hinge for aligning thebracing sections relative to the joint. This alignment permits accurateplacement of the axis of rotation of the device to recreate the normalkinematics of the joint.

The hinge also includes a gear mechanism which can be used for movingthe bracing sections and consequently their respective limbs relative toeach other through the application of external force to the gearmechanism. The external force can be applied through a manually operatedcrank or a motor in order to stretch soft tissue surrounding the jointand thereby address a joint contracture. A clutch is also provided sothat the gear mechanism can be disengaged for allowing the limbs to movefreely under the patient's own muscle force through flexion andextension.

An adjustment mechanism can also be provided for placing the joint indistraction and maintaining its alignment in that position while theskeletal elements are moved through flexion and extension.

By providing the mechanism as described, contractures in the vicinity ofa joint, such as an elbow, can be prevented through active or passivemovement of the limb through the joint. Continuous passive motion can beapplied to the joint with proper tracking and concomitant stability thatcomes from maintaining the skeletal elements in proper orientationrelative to each other while they are being moved.

Further, the subject dynamic joint support also allows the joint to beheld in distraction while permitting an active range of motion. All ofthe above can be performed without pins or wires in close proximity tothe joint which eliminates skin irritation because there will be lessskin motion relative to the underlying bone during movement of thelimbs. Further, the location of the pins is discretionary with thephysician so that pins can be placed away from a fracture and notinterfere with the healing process of a fracture in the vicinity of thejoint. In addition, the apparatus may be designed to permit unrestrictedaccess to the anterior portion of the joint for medical and surgicalprocedures.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the invention can be obtained from thedetailed description of a preferred embodiment set forth below, whenconsidered in conjunction with the appended drawings, in which:

FIG. 1 is a side plan view of the dynamic elbow brace which is thesubject of the present invention, as the brace would be connected to anarm of a patient in extension;

FIG. 2 is a bottom plan view of the dynamic elbow brace shown with adashed line depiction of the axis of the underlying bones;

FIG. 3 is a partial plan view of a support ring, for fixing the supportto the bone;

FIG. 4 is similar to FIG. 3, showing a support ring which only partiallyencircles the limb.

FIG. 5 is a side plan view of the dynamic elbow brace, as it would beconnected to the arm of a patient in flexion;

FIG. 6 is a top view of the proximal bracing section;

FIG. 7 is a side plan view partially in section of the hinge and thegear mechanism;

FIG. 8 is a top plan view partially in section showing the engagedclutch mechanism;

FIG. 9 is a top plan view partially in section showing the disengagedclutch mechanism.;

FIG. 10 is a perspective view of the hinge showing the clutch mechanism;

FIG. 11 is a sectional view of the disengaged gear mechanism;

FIG. 12 is a plan view partially in section of the gear mechanism andthe drive shaft;

FIG. 13 is a side plan view of the hinge showing the distractionmechanism;

FIG. 14 is a side plan view of an alternative embodiment of theinvention, as it would be attached to an arm in partial flexion;

FIG. 15 is a similar view as FIG. 14, with the arm in extension;

FIG. 16 is a side plan view partially in section showing the gearmechanism of the alternative embodiment.

DETAILED DESCRIPTION OF THE INVENTION

The dynamic joint support in a preferred embodiment of the presentinvention is shown as it would be connected to the arm of a patient inFIGS. 1 and 2, where reference numeral 10 identifies dashed linesillustrating the forearm of the patient and 12 the upper arm. Thesupport includes a pair of hinges 14 which are collinear or aligned withthe kinematic axis of the elbow as shown by center line 16 (see FIG. 2).This alignment can be accomplished through the use of an X-ray machine(not shown) which can center the hinge through radio-opaque cross hairs18 provided in a central window 20 formed in the hinge 14, which istransparent to X-rays.

Each hinge 14 includes a pair of fitted plates 22, 24 which are adaptedto rotate relative to each other and are respectively connected toarcuate members 30, 32 (FIG. 7). The connection of the rotating plates22, 24 to the arcuate members 30,32 may be direct, as shown in FIGS. 6and 7, or indirect, through radially-extending arms 26, 28 as shown inFIG. 14.

Referring again to FIGS. 1 and 2, distal adjustment blocks 34, 36connect the hinges 14 to one or more annular support rings 38.Alternatively, as shown in FIG. 15, the hinges 14 may be connected toone or more annular support rings 38 by threaded rods 40.

As shown in FIGS. 3 and 4, the annular support rings 38 may be formed ina closed or partial circle and contain a plurality of openings 41 aroundtheir circumference. The support rings 38, 58 can be similar to onesdeveloped by Dr. Ilizarov for use in bone lengthening or rehabilitationtechniques, which are commonly known as Ilizarov rings.

Rods 44 extend between the annular support rings 38 when more than oneis used. Wires 46 or pins (not shown) attached to the annular supportrings 38 or to the extending rods 44 are embedded in the ulna forholding the support ring 38 rigidly in place relative to the forearm 10.(While pins might likewise be placed in the radius, because ofinterference with the motions of supination and pronation, suchplacement is not preferred.)

Proximal adjustment blocks 54, 56 or rod 60 in the embodiment of FIGS.14-16 likewise connect the hinges 14 to one or more annular supportrings 58 which are connected to the humerus through a series of pins 60or wires 66 which are in turn connected to the support rings 58 orthrough rods 64.

As shown in FIG. 2, the hinges 14 are located both medial and lateral tothe elbow joint along with corresponding adjustment blocks 34, 36 and54, 56. Also, arcuate members 30, 32 of the hinges 14 are located onboth sides of the joint.

The hinges 14, the adjustment blocks 34, 36 and 54, 56, rods 44, 64 andthe support rings 38, 58 form external bracing sections which can beconnected to the respective bones in the forearm and upper arm. Throughthe hinges 14, these elements allow the arm of the patient to movebetween the extended position of FIG. 1, where the arm is relativelystraight, and the flexed position of FIG. 5, where the forearm 10 andupper arm 12 are moved toward each other. As described in detail below,the bracing sections can be precisely aligned with the kinematic axis ofthe joint so that when the extension and flexion described above takesplace, contractures are prevented, reduced or eliminated.

As shown best in FIG. 7, the arcuate member 30 is formed as a curvedrack which mates with a worm 70 located in a housing 72 mounted onarcuate member 32. The housing 72 is hollow, to allow the curved rack 30to telescope within the arcuate arm 32 as the worm 70 is moved throughrotation of a miter gear 74. A crank 76 can be connected to the mitergear 74 which, when turned manually, will effect extension and flexionof the arm of the patient. Alternatively, a suitable connection can beprovided for connecting a motor to the miter gear 74 for effectingcontinuous passive motion to the arm of the patient.

Referring now to FIGS. 8 and 9, a clutch 78 can be provided forselectively disengaging the curved rack 30 from the worm mechanism 70 sothat the patient can use his or her own power to extend or flex the arm.The clutch 78 may be for example, a set screw or crank which, whenengaged, as showing in FIG. 8, causes the curved rack 30 to engage theworm 70. When the clutch 78 is disengaged, as shown in FIGS. 9 and 11,the curved rack 30 is disengaged from contact with the worm 70, andpermits free movement of the arcuate members 30, 32 relative to eachother.

The arcuate members 30, 32 on the opposing sides of the elbow joint caneach move relative to each other as described above. Only one hinge ofthe two opposing hinges on each side of the joint requires the gearingmechanism as described. Referring to FIGS. 2 and 12, a drive shaft 80 isconnected between the gear housing 72 of each hinge 14, and transfersrotational energy from one hinge to the opposite hinge. Turning of thecrank 76 of one hinge thus drives each hinge in synchrony through thedrive shaft 80.

The drive shaft 80 may extend between the hinges either anterior orposterior to the joint. Because of the incidence of anterior swelling intrauma to the elbow joint, it is generally preferred that the driveshaft 80 be positioned posterior to the elbow joint. For ease of patientuse, it may be preferred that the crank be located on the medial aspectof the elbow joint.

While only one gear mechanism is required, it is preferred that bothhinges 14 contain the complete gear system. Having the gear mechanismavailable on each side of the joint provides more accurate tracking ofthe arcuate members 30, 32, allows the device to be interchangeablebetween right and left arms, and also allows maximal flexibility ofpatient and physician use. In the preferred embodiment, turning of onecrank 76 provides rotational energy to the drive shaft 80, whichprovides rotational energy to the miter gears 74 and worms 70 of bothhinges in synchrony.

Referring to FIG. 5, the dynamic support of the present invention isshown installed by first connecting the support rings 38, 58 to bones ofthe patient's arm using pins 45 or wires 46, with the remainder of theapparatus loosely connected and generally aligned. The proximal supportring 58 is oriented perpendicular to the proximal humerus of the arm 12,while the distal support ring 38 is oriented perpendicular to the ulnaof the forearm 10. The extended rods 44, 64 are threaded withcorresponding nuts 82, 84 so that the location of the hinge 14 can beadjusted in length relative to the support rings 38, 58 in the directionof arrows 86, 88.

As shown in FIGS. 3 and 4, openings 42 in the support rings 38, 58 areelongated so the hinge 14 can be adjusted circumferentially relative tothe stabilized bone, as illustrated by arrows 87, 89 in FIG. 5.Rotational adjustments can be made as described above between thesupport ring 58 and the proximal adjustment blocks 54, 56 by way of theelongated slots 42 of the support ring 58. Once positioned rotationally,the support ring 58 is held tightly in place, for example, by tighteningof screws 94 through the elongated slots 42 and into the adjustmentblock 54, 56.

The natural axis of the forearm of a patient 10 is offset from the axisof the upper arm 12 by approximately 7°. Proper alignment of theexternal support sections on opposite sides of the hinge is necessary inorder to maintain the proper angle of the bones during extension andflexion. As shown in FIG. 2, to accommodate for this natural angle ofthe elbow joint, the lateral proximal adjustment block 54 is larger insize with respect to the medial proximal adjustment block 56. It isimportant that the variation in the medial and lateral blocks compensatefor the 7° angle at the axis of the elbow joint.

It is contemplated that the device may be interchangeable between theright and left arms by exchanging the medial and lateral proximaladjustment blocks. It is also contemplated that proximal adjustmentblocks of varied sizes may be substituted to compensate for variation inthe distance between the hinges, for example, when treating a childversus an adult.

As shown in FIGS. 6 and 7, the proximal adjustment block 54, 56 includesa sliding block 90 and a track 92 in which the sliding block 90 slidesto adjust the location of the hinge 14 in the anterior-posteriordirection (arrow 91) relative to the proximal support ring 58 andthereby relative to the stabilized bone.

As shown in detail in FIG. 13, the distal support ring 38 is connectedto the hinge 14 through the distal adjustment blocks 34, 36. Whendistraction of the joint is desired, the distal adjustment blocks 34, 36allow the hinge 14 to be moved along a line about 30° relative to a lineperpendicular to the bones of the forearm. This can be accomplished, forexample, by turning a set screw 96 which moves a boss 97 in a track 99to cause movement of the distal adjustment blocks 34, 36 along the line98. This movement of the distal adjustment blocks allows the attachedbones of the forearm to be distracted, or to be moved slightly out ofcontact with the humerus with the device, permitting motion of the jointduring distraction. Distraction of the joint may be desired in treatmentof injuries to the joint itself.

Through the mechanism described, the dynamic elbow support can beaccurately aligned with the kinematic axis of the elbow through the useof an X-ray machine by aligning the cross hairs 18 in the X-raytransparent portions of the hinges 14. Fine adjustments can be madethrough the proximal and/or distal adjustment blocks 54, 56 and 34, 36.Once the dynamic elbow brace is accurately aligned in the preferredposition, a patient can have his or her arm extended or flexed throughthe application of manual movement to the gearing mechanism or throughconnection to a motor for continuous passive movement. The clutchmechanism can be employed to disengage the curved rack from the worm sothat the patient can actively move his or her arm through full extensionand flexion.

The dynamic elbow brace of the present invention is useful in thetreatment of trauma to the arm and forearm such as severe fractures,dislocations of the elbow and the like as well as the treatment oftrauma to other joints where a high possibility of fracture andstiffness normally results from immobilization. The apparatus may beapplied to the patient immediately to begin rehabilitation and preventcontracture. In some instances, it may be desirable to apply distractionto reduce the joint reaction force during flexion and extension. Thedynamic brace allows for all of these treatments to occur throughapparatus which is connected to bones on opposite sides of the jointdistant from the joint so as not to interfere with movement andrehabilitation.

The dynamic joint brace of the present invention also permitsreadjustments as needed during therapy without significant interferenceusing external adjustment mechanisms. Adjustments may be necessary ifthe patient should fall or otherwise disturb the set alignment duringtherapy. Alternatively, the device permits monitored therapy, withimmediate and easily accomplished adjustments in the proper alignment.Adjustments may be made in rotation, anterior-posterior positioning, anddistal-proximal positioning of the hinge relative to the fixed skeletalelements.

The dynamic joint brace of the present invention may be fabricated usingmaterials known in the field. It is preferred that the materials used tofabricate the device permit sterilization of the device.

The foregoing description is considered to be illustrative and notlimiting and variations and improvements to the invention can be madewithout departing from the spirit and scope of the invention. All suchvariations and improvements are contemplated as falling within the scopeof the appended claims, which

I claim:
 1. A dynamic support, comprising:proximal and distal externalsupport sections, one for each skeletal element on opposite sides of ajoint; connecting means for rigidly connecting each support section to abone on its respective side of the joint, wherein said connecting meansattaches to the bone at a distance from the joint and not at the axis ofrotation of the joint; hinge means having an axis for connecting thesupport sections to each other in the vicinity of the joint so the hingemeans will pivot the joint when the skeletal elements move throughflexion and extension; and x-ray transparent means at the pivot point ofthe hinge means having radio-opaque indicia means for enabling alignmentof the axis of the hinge means with the axis of the joint.
 2. Thedynamic joint support of claim 1, comprising:adjustment means foradjusting the position and orientation of the hinge relative to therespective support sections and relative to the axis of the joint. 3.The dynamic joint support of claim 1, wherein the hinge means includes agear means for moving the support sections and consequently theirrespective skeletal elements through flexion and extensions in responseto the application of external force to the gear means.
 4. The dynamicjoint support of claim 1, further comprising:distraction means forstably fixing bones of the joint out of contact with each other.
 5. Adynamic joint support comprising:proximal and distal external supportsections, one for each skeletal element on opposite sides of a joint;connecting means for rigidly connecting each support section to a boneon its respective side of the joint, wherein said connecting meansattaches to the bone at a distance from the joint and not at the axis ofrotation of the joint; hinge means for connecting the support sectionsto each other in the vicinity of the joint so the hinge means will pivotthe joint when the skeletal elements move through flexion and extension,wherein the hinge means includes a gear means having two gear sectionsfor moving the support sections and consequently their respectiveskeletal elements through flexion and extension in response to theapplication of external force to the gear means; and clutch meansconnected to said gear means for selectively engaging said gear sectionssuch that the force is transferred between said gear sections torestrict free motion of the skeletal elements and permit controlledextension and flexion of the joint and for selectively disengaging thegear sections to allow the skeletal elements to move freely.